The present invention relates to devices for observing the interior of a body, living or manufactured, comprising a flexible conduit for transmitting images from the interior of the body to an image display device that is outside of the body. In these devices, the flexibility of the conduit makes it possible to pass through a part of the body, linking a zone to be observed that is inside the body, to an external viewing console.
The conduit must be flexible enough for it to penetrate into regions of the body that may be particularly convoluted.
Usually the conduit must also be sufficiently rigid to permit guiding of an examination tip of the conduit, from outside the body, by action on the conduit.
In many devices of this type, the conduit is manipulated in order to gain access, at an illumination end of this conduit, adjacent to the body, to a region for observation within the body which is inaccessible directly from outside the body with photon radiation.
These devices therefore usually constitute means for examining regions that are inaccessible to direct observation.
When the body to be observed is the body of a living being, such devices are generally called endoscopes.
The known endoscopes are often based on a principle of overall illumination of a field, in poly- or monochromatic light. Light is transmitted via an illumination channel, and the visual information is transmitted through another channel.
With these endoscopes, observation is by means of a photographic sensitive surface or a CCD camera. They therefore require high levels of illumination.
Their performance level is determined essentially by the optical resolution of a system for carrying the images and by the quality of an optical system. They do not permit observations to be made with satisfactory depth resolution, nor do they give acceptable contrast, especially in diffusing environments.
Furthermore, these devices are unable to provide, simultaneously, a large viewing field and a wide numerical aperture in a confined space.
An endoscope has also been proposed, in document U.S. Pat. No. 5,074,642, comprising a bundle of fibres of which the end towards the observer is positioned opposite a light source and is vibrated opposite this light source, the various fibres are scanned by the source, and scanning of a region of the body is thus obtained.
Such a device only permits very slow scanning of the fibres and in particular proves to be too slow for obtaining a video image in real time.
In the field of microscopy, devices called xe2x80x9cconfocal microscopesxe2x80x9d have been proposed. These devices cannot be used for endoscopic examination. Confocal microscopes are used for various types of microscopic examination, such as examination of sections by transillumination, or direct anatomical observation by back-illumination, or investigation with the aid of dyes such as fluorescein, indocyanine green or acridine orange.
With certain recent experimental systems, functional investigations are also possible, such as investigation of functional activities of the cerebral pathways or evaluation of the condition of vessel walls. However, observation of cerebral neurologic activity, for example, can only be carried out on animals, as it is necessary to carry out an ablation of the top of the skull to mount a confocal microscope for observation.
Document DE 42 07 092 also proposes an endo-scope that has a bundle of optical fibres for conveying an image from the observed object to the observer. This document proposes means for scanning a beam in this grating of fibres, but this bundle is used solely for a therapeutic treatment and not for illuminating a region for the purpose of observation. The illumination is an overall illumination.
One aim of the present invention is to propose a device for viewing the interior of a body, such as the body of a living being, comprising means for illuminating the interior of the body, a means of displaying an image, and a flexible conduit that is to pass through an internal region of the body and convey an image from the interior of the body to the display means, which provides a particularly clear image of an observation region inside the body (by confocal techniques or by techniques based on interferometry).
Another aim of the present invention is to propose a device of the endoscope type giving acceptable depth resolution and contrast, even in diffusing media under observation.
Another aim of the invention is to propose an endoscope with high photon sensitivity.
Another aim is to propose a device permitting spatial and temporal separation of the parasitic flux associated with the illumination of that corresponding to tissue reflection.
Another aim is to propose a device that limits reflection in overlying and underlying diffusing media of a tissue medium being examined.
Another aim is to propose a device that makes it possible to eliminate reflections associated with optical mounting elements.
The invention also aims to propose a device that permits the formation of a tissue image with a wide-aperture exploratory light beam by placing the optical device in contact with or a few millimetres away from the tissues or surfaces to be examined.
According to another aim, the invention proposes a device that can withstand possible vibration of the mounting and does not require special maintenance or adjustment.
Another aim of the invention is to supply a device that can provide a satisfactory resolution with a group of fibres of small diameter.
A further aim of the invention is to supply a viewing device that does not have, in its part adjacent to the body being examined, any electronic or mechanical part that is likely to be attracted or damaged when submitted to an intense magnetic field, so that it can be used in conjunction with a device for observation by magnetic resonance.
It also aims to permit particularly rapid scanning of optical fibres.
These various aims are achieved by means of a device for observing the interior of a body, comprising a means of displaying an image, a group of fibres gathered together side by side and intended to pass through an internal part of the body to convey an image from the interior of the body to a display means, illumination means provided for scanning the fibres of the group of fibres, positioned at the end of the fibres that is farthest from the body, characterized in that the illumination means include means for imparting successive angular deflections to an illumination beam, means for converting the angular scan obtained to a lateral scan relative to a principal axis of entry of the group of fibres, in that the means for scanning the fibres are external to the group of fibres and in that the group of fibres forms an image guide whose ends are arranged in the same order at both ends of the guide.